1. Field
The present invention relates to a fuel for a fuel cell, and more particularly to a fuel for use in a fuel cell such as a direct methanol fuel cell (DMFC) of the active type.
2. Description of the Related Art
An active type DMFC of this kind is a voltaic cell comprising an anode (fuel electrode) to which a mixed solution of water and methanol is supplied as a fuel, a cathode (air electrode) to which an oxidizing agent (oxygen, air) is supplied, and a polymer electrolyte membrane interposed between the anode and the cathode. The anode is composed of a catalyst layer which contacts with the polymer electrolyte membrane, and a diffusion layer such as a carbon paper laminated on the catalyst layer. The cathode is composed of a catalyst layer which contacts with the polymer electrolyte membrane, and a diffusion layer such as a carbon paper laminated on the catalyst layer.
When the active type DMFC operates in a low temperature environment such as a cold district, the fuel, that is, the mixed solution of water and methanol freezes, and the output is lowered.
Hence, Jpn. Pat. Appln. KOKAI Publication No. 2004-6335 discloses that a fuel for a fuel cell is prepared by adding polyhydric alcohol such as ethylene glycol or propylene glycol as an antifreeze to a mixed solution of water and methanol. However, when the fuel having polyhydric alcohol such as ethylene glycol or propylene glycol added thereto is supplied to an anode (fuel electrode) of the fuel cell, a catalyst of the fuel electrode (for example, a platinum-ruthenium catalyst) is poisoned, and the output of the fuel cell is lowered.